Because of these risks, Hawking says that instead of seeking aliens out, humanity should be doing all it can to avoid any contact. Well, perhaps, but I don't think his hypothesis provides valid reasons.

Who am I to question Stephen Hawking, one of the worlds best physicists? Although I respect Hawking and the work he has done, when it comes to speculating about intelligent aliens, I have as much information about extraterrestrials as he does. Namely, None! And that puts my speculations at least as on par with his.

As for point 1, of course I don't know (nor anyone else) whether alien life exists in other parts of the universe, but I do think it possible and for the sake of argument I agree that life "almost certainly exists in many other parts of the universe."

I also agree with point 2, that it presents a challenge to work out what aliens might actually be like, especially when we don't have a shred of evidence for their existence.

My skepticism aims at points 3 and 4.

In all due respects, Hawking hasn't hypothesized anything new here. The idea of aliens looking to conquer earth has been expressed in science fiction stories from H.G. Wells' "The War of the Worlds" to "V" the TV series about an advanced alien species that visits Earth for sinister motives. Many other people have also questioned the motives of sending out messages to aliens. Ever since the Golden Record was sent abroad the Voyager spacecraft in 1977, even some astronomers and those within the SETI organization have speculated that extraterrestrials might hold hostility toward other planetary life forms. (For examples, see this, this, and this.)

Why I don't think alien visitors would be hostile

Here are some of the reasons why I don't think we will meet hostile extraterrestrial aliens:

1.

To survive, an intelligent species would have to control any tendency toward hostility. Risk total annihilation

or learn to coexist peacefully.

2.

An extraterrestrial spaceship would require carrying biological baggage that would prevent practical

space travel to other solar systems.

3.

Even if extraterrestrials found the means to travel such vast distances, they would need to adapt to space,

thus eliminating the need for conquering other worlds. (They are already surviving.)

4.

Even if they had the means to overtake another world for their survival means, why not pick an uninhabited

world rather than an inhabited one? (it's easier.)

5.

It appears more likely that intergalactic (not extraterrestrial) life forms would live in space and they would

have no need for hostility.

I covered many of these reasons in my speculations on Death and Time Traveling but I will briefly outline my reasons here.

The main reason why Hawking and others think that aliens might prove hostile comes only by comparing them with the only life they know of. Earth life, especially, us. However, human hostility to other life forms and to our human neighbors comes more from our cultural history rather than from biological evolution. Does human nature require hostility toward other beings? Perhaps it did in our past evolutionary history but as we continue to evolve, I don't think it's necessary considering the plasticity of our nature. Human cultures throughout history have varied dramatically, ranging from extreme hostility to peaceful, and our tendency over time has been toward peace rather than toward establishing ourselves as a conquering specie. When Hawking compares aliens to what Christopher Columbus did to natives, he ignores that the Christian history of slavery and conquest against pagans lasted less than 1500 years, a fraction of time in the history of human culture. Most Christians today do not have such a conquering attitude (except for a few right-wing radicals).

Stephen Pinker, for example, provides a strong argument for the myth of human violence. Some people may disagree, but even if you think human nature as innately hostile, what end would it eventually meet? Many have speculated that we will end up destroying ourselves. The same goes with intelligent alien life because they would undoubtedly eventually discover E=MC2 and they could very well exterminate themselves by blowing themselves up in a nuclear war or by other means. If so, there would be few conquering aliens to fear.

By definition, an extraterrestrial being lives on another terrestrial planet, and that presumes to mean that it evolved in some biological way, similar to human evolution, in another solar system. After all, we are comparing extraterrestrial aliens to humans, the only intelligent animals we know of that has the capability of traveling in space.

It seems to me that if we are to survive as a human specie, we had better learn to solve our hostile cultural natures or risk exterminating ourselves through nuclear, biological, or other means. This means learning to avoid war and conquest and to understand the dangers of our belief systems. I suspect the same goes with aliens. So if there is any tendency for hostility, a hostile species will most likely eventually die out or, if any survived, they will have learned to tame their biological natures. (As Robert Axelrod demonstrated, Iron Rule strategies never work out in the end.)

Any intelligent extraterrestrial being would need to carry on board its spaceship all the necessary biological requirements including an atmosphere (presumably to breath, or "absorb"), food, and water (or whatever liquid they require), and the living conditions that would satisfy their biological needs that may include sleep, exercise, communication, entertainment, etc. Although this may be realizable for inter-solar travel, the time required to travel from star to star would mean carrying on board almost impossible amounts of cargo to meet its biological demands. Not only would they need to carry their survival baggage, but they would need to develop and carry the weapons necessary to take over another world. And what weapons should they carry? They would need to know about human technology before they develop the weapons necessary for their overtake.

But lets say these conquering aliens did manage to solve the means to travel vast distances through space. Perhaps their spaceships are so large that they have the means to satisfy their biological natures. They might learn to grow (or raise) their food within the spaceship as a sort of mini-planet like that proposed by Gerald O'Neill in the 70s. They might have a regenerating atmosphere, and a "society" of aliens to keep them happy. They might even have learned to extend their lives through genetic manipulation. But here's the problem. If they have learned to survive in space over vast distances and time, then why would they need to conquer another world? Since they would need to develop a means to satisfy all their living requirement for years, if not hundreds or thousands of years (even if they traveled at light speed), then they would not need Earth's resources for their survival, would they?

Considering all these obstacles, even if they still aimed to conquer for means of their survival, why would they choose an inhabited world? Why not go the easiest route by picking an uninhabited planet? Lets say they needed to find a water planet, such as Earth. There is already evidence within our solar system that water exists on other planets. We have already discovered water on Mars, on Earth's moon, on asteroids and comets. Scientists claim that Europa, a moon of Jupiter, has more liquid water beneath its icy crust than Earth. There are, no doubt, far more uninhabited water worlds even within the "Goldilocks Zones" in other solar systems than there are worlds inhabited by intelligent beings. So why not avoid unnecessary conflict by simply choosing an uninhabited world?

I suspect that looking for intelligent beings on other planets will turn out to be rare if not almost impossible to find. Why? Because (again using humans as our only analogy) intelligent beings would exist for only a very brief evolutionary time on a planet. Homo sapiens, for example, evolved large brains very rapidly (evolutionary speaking) within 3 or 4 million years. We now are approaching the means to modify our own genes through cultural evolution (memes) and our evolutionary nature should expand exponentially. My guess is that either we will destroy ourselves or we will shortly evolve into a non-biological specie. In fact, we have already started to do so. Today, more and more people live through computers, cell phones and virtual realities. We wear watches, hearing aids, and some of us spend more waking time watching computer and TV screens than looking at real life. We have begun to implant into our bodies artificial hearing devices, artificial eyes, heart pumps, valves, artificial voices, etc. Stephen Hawking himself, depends on mechanical means to keep him alive and communicating! We have just begun to understand memristors, a new type of circuit element that mimics neurological function. It's only a matter of time before we can replace any organ in the body, including our neurons, and the very thoughts and emotions that emerge from them.

Once we achieve complete body replacement, including our brains, intergalactic travel to the stars becomes not only possible but probable, and I suspect the same would occur for intelligent extraterrestrials. If I am right, then the period of intelligence on terrestrial planets would probably be relatively short, perhaps only around 4 to 10 million years. This short window of time does not allow much chance for an intelligent being to be found on a planet, maybe because they would have moved on and learned to adapt to a new environment: space. Perhaps if we humans removed our heads from our religious asses, we could learn to live in space instead of waiting for Armageddon.

How would aliens live in space?

Unlike a planet that has limited resources (and thus the need for some species to be hostile), there are virtually no lack of resources in the universe. An intelligent nonbiological being that learned to live and evolve in space would have no need for hostile intentions toward terrestrial beings because terrestrials would not be necessary for their survival. It's as simple as that. Consider that a nonbiological being would not need to carry biological life supplies to live on. No need to carry an atmosphere; no food or large amounts of water to transport and consume. Like a solar powered computer, a cyber-life-form could live off starlight. Its spaceship would not need to travel near light speed because the cyber-being could shut down its "circuits" while traveling at sub-light velocity through space. Its conscious life would consist of bursts of microseconds during traveling time, in what I describe as "duty-cycle spacetime travel." In effect, this is a type of time travel into the future without resorting to speculative wormholes or extra dimensions. Nothing about duty-cycle time travel goes against the known physics of the universe.

Duty-cycle spacetime travel

From the perspective of a conscious space-traveling alien cyber-being, its mental flow of consciousness would appear continuous even though its mental circuits would stay on only for a brief periods of time. A duty cycle represents an electronic description of a ratio of a pulse duration (t) in a period of time (T). Thus the Duty Cycle of the "consciousness" of the alien cyber-life would occur only during the pulse durations through time. Each pulse might occur only at microsecond intervals through a time period of hundreds if not thousands of years in universal time. Moreover, their communications between each other would also be duty cycled. Thus, the cyber-alien would, in effect, have the ability to travel through spacetime without living through the boring periods between stars. From the perspective of a terrestrial intelligent being (like us) these alien time travelers would not be easily found simply because of the vast distances and time between their transmissions. Any form of communication by us to them, would be missed. More likely, it wouldn't make much difference if we tried to communicate with them anyway because, after all, we have already been sending out messages of our existence at lightspeed in space for years through our radio and TV transmissions. Transmitting for reasons of finding aliens would hardly add much to the problem.

If these intergalactic beings exist, no doubt they would be intelligent and would possess curiosity about the universe. After all, in order to survive the vast distances of time and distance, they would need to accumulate as much information about the universe as possible to help them survive against entropy, black holes, intergalactic matter, etc. No doubt they would have a history about themselves and would be curious about how other life forms evolved. Human biologists also have curiosity about lower life forms, so I would expect our aliens to possess scientific curiosity as well. If the aliens wanted to visit an inhabited terrestrial world, I suspect it would be for knowledge rather than to overtake or to conquer. At worst they may look at us as a species for study and perhaps they might even take a few of our members for samples rather than for total elimination of our species. But again, if we're comparing them to us, even here it might be to naive to think they might harm us even for scientific studies.

Today there are scientists and animal activists who recognize that other animals have feelings and emotions like us. These people fight for the rights of animals and to prevent pain and suffering. Why wouldn't an advanced intelligent life form also recognize the pain and suffering of other species even more?

Search for interstellar aliens, not extraterrestrials

For the reasons stated above, I think the search for intelligent extraterrestrial aliens don't stand much of a chance of success, and I think the SETI project has looked for the wrong type of alien. I think it is far more likely (although still unlikely) to find interstellar aliens living in space rather than aliens living on terrestrial planets. (The search for lower life forms, microbes, bacteria, however, represent a different kind of search and we should look for these on other planets. Here I do think we will have success.)

So where in space should we search for intelligent aliens? Because of the vast distances of space and the probability (in my opinion) that interstellar aliens live in time delayed duty cycles, we should look where they have the best chance of survival. This means they probably won't live around dark holes or centers of galaxies because of the dangers of extreme gravity, debris, intense radiation, and heat. Instead, look for them at the outer edges of galaxies, where there are fewer asteroids and comets. Possibly we might find them mining the remnants of super novas to gather the heavy elements necessary for building their spaceships and their "bodies," or perhaps the spaceships are their bodies (here are two sketches of my ideas of what they might look like, here, and here). For fuel, they might gather hydrogen from interstellar gas clouds, or they may have solved the fussion problem, which would allow them to carry a mini-star on board their starships.

Nor should we try to send signals to the aliens, not because we should fear hostility, but because the costs of transmission outweighs the benefits and lower costs of listening for them through receivers and radio telescopes. Besides, the time it would take for the aliens to answer us would take years for their messages to get to us. So, how should we listen for them?

I'm guessing that interstellar aliens have deployed navigation and communication "buoys" at various stationary spots throughout the galaxy to help them get around and to talk to each other (if we were traveling through intergalactic space, in mass, wouldn't we do so as well?) If so, these transmission buoys would probably be sending out signals much stronger and more continuously than the alien spaceships themselves. So instead of aiming our receivers at planets, look for dark areas in space within our galaxy that might serve as the best places to plant these buoys.

To speculate even further, I'm guessing that intergalactic alien populations are extremely high, perhaps in the trillions. On Earth, life form populations are limited by the environmental niches they live in and by competing predators. But even on Earth, a few life forms such as coral, can expand vast areas as long as the environment allows it. Some coral reefs are so expansive that they can be seen from space! [see photo]. In the vast space volumes between stars, there are virtually no limitations. Even if it is extremely unlikely that a terrestrial alien specie evolved to live in space, it only had to happen once. Just like the unlikelihood of DNA based life originating on our planet, it too only had to happen once. And once life started, natural selection took hold, and today our planet is filled will life. Moreover, the history of evolution on earth shows that more species die out than survive. This is because of competition by other species, natural disasters, disease, etc., and the fact that all life forms on earth die (without death a terrestrial specie could not evolve). A non-biological alien specie living in space, on the other hand, should have no competition. Its knowledge about the universe would allow it to avoid natural disasters, and since it is nonbiological, it wouldn't have life threatening diseases. Without terrestrial biological limitations, space-born aliens could evolve, unimpeded, for millions of years, if not billions of years, an without the need for any of them dying. If such vast populations exist, they would appear like dark matter to us, living in super-slow time frames sending out signals only during their rare "waking" periods. They should be intelligent and altruistic to themselves as well as all life forms, including humans. I see no reason to fear them.